The racial and ethnic tensions that came to the forefront during this year’s presidential contest were felt in Washington-area schools in the days after the election, with threats, swastikas painted on walls and racist attacks alarming educators, parents and students.

Administrators at a Bethesda middle school found numerous images of a swastika drawn on the wall of a boys’ bathroom Friday, the second such incident at the school in the past two weeks.

In a letter sent to parents of students at Westland Middle School, Principal Alison L. Serino said administrators have contacted the Montgomery County Police Department to investigate the acts of vandalism.

“We are very saddened by this incident,” Serino wrote. “This type of behavior will not be tolerated. Once the culprit(s) are identified, consequences will be administered in accordance with the MCPS Student Code of Conduct.”

In an interview Friday, Serino said that she was “sad and disturbed” about the incidents, and that she and her staff are planning to address the issue with students when they return to school for the coming week.

“I think we need to double down on our efforts about respect, knowledge of one another and understanding where people are coming from,” she said. “I think it’s a really important time to be an educator.”

Serino said that the incidents have caused “concern and worry” for the school’s students. She added that while the school year has been mostly typical so far, “there is heightened awareness around race, ethnicity and religion” as a result of the tense presidential campaign, which drew on adult themes and has elicited racist and xenophobic acts nationwide.

School districts nationwide have been addressing heightened emotions as they navigate how to teach the outcome of the election. Superintendents and principals have been imploring their communities to embrace civil discourse and to use the election as a teachable moment. Yet there have been numerous examples of intolerance that have spurred concerns about the physical and psychological safety of students.

Officials in suburban Maryland are investigating an incident involving a white student who posted a photo of herself in blackface on social media, with a caption that used a racial epithet.

The principal of Atholton High School, in Columbia, Md., said in an email to families Thursday that administrators became aware of the photo as school let out that afternoon.

The letter, signed by Principal JoAnn Hutchens, described the image as a “racially offensive and hurtful post,” and said school officials were in contact with the student’s parents and would take appropriate action.

“I am committed to ensuring a safe and inclusive environment for all students at Atholton High School,” she wrote. “I encourage all students to ‘Think Before You Post.’ ”

Howard County school officials said Friday that students who saw the image brought it to the attention of the principal and that soon afterward the teenager’s parents also contacted Hutchens.

They said the image appeared to have been posted to an image-sharing app and then was reposted on other platforms.

The caption on the blackface photo said, “im finally a n-----.”

Howard school spokesman John White said the student, an 11th-grader whom district officials did not identify, was “very apologetic” about what she had done.

White said the district is working with the family as it investigates and would follow its student code of conduct in applying consequences. Under the code, disciplinary action may be taken for off-campus incidents that could have an adverse effect on schools.

Howard has seen other incidents of racial hatred, including a student’s social-media video last year that denigrated the value of black lives. District officials said Friday that the most recent episode reinforces the need for a community meeting — already planned for Monday night — to discuss the responsible use of technology and social media, and supporting an inclusive community.

“Too many young people and adults post things without thinking about what happens next,” White said. “We want to make sure parents know about the latest technology and that students know there could be ramifications for a bad decision.”

There have been a few instances of students hurling insults at others in the wake of the election in Loudoun County, Va., according to Wayde Byard, a spokesman for Loudoun County Public Schools. Byard said students in middle school and high school have been repeating lines they have heard on the campaign trail, including “build the wall” and “drain the swamp.”

“What we’re seeing is nervousness on the part of our English-language-learning population. A lot of them have escaped war-torn places, and they are terrified of going back to those places,” Byard said, referring to the county’s growing immigrant population and fears of deportation under a new president. “There have been untoward comments — nothing that is confrontational, more of gloating.”

Byard said that most of the confrontations occur in the cafeteria and the halls as students are switching classes. The school system has asked teachers to have a presence in public areas to deter such comments.

“Most of the time people are saying these things flippantly, and they think it’s funny,” he said. “They’re not realizing how it might affect people.”